This invention generally relates to a shift motor encoder assembly and more particularly, to a shift motor encoder assembly for use with a four wheel drive transfer assembly and which utilizes an improved encoding methodology which reduces the likelihood of faulty operation and malfunction.
A four wheel drive system typically includes a transfer assembly (e.g., a xe2x80x9ctransfer casexe2x80x9d) which operatively receives a selectively rotating input shaft which receives torque from an energy source, such as an internal combustion engine, and a pair of driveshafts (e.g., a front and a rear driveshaft). The transfer assembly further includes a selectively positionable motor which selectively and movably couples or decouples the input shaft to one or both driveshafts in a desired and selected manner, with or without a gear depending upon the position of the motor or the spatial orientation of a portion of the motor, such as the shaft member.
Particularly, the motor is communicatively coupled to a controller which selectively causes the shaft or other portion of the motor to occupy a certain desired portion. The controller is further coupled to an encoder Assembly, effective to allow the controller to ascertain the motor position and other attributes of the motor. Typically, communication-between the encoder assembly and the controller occurs by the use of binary signals and the codes for various motor positions are based on a particular binary encoding methodology by design. While such methodologies or encoding schemes do allow the controller to ascertain the position of the motor, they are prone to error and prone to causing undesired malfunction or errant operation which may cause undesired damage to the transfer assembly and/or vehicle malfunction (e.g., should an error occur in the communication channels, both the encoder assembly and the controller, the controller may be errantly informed of the position of the motor and attempt to cause the motor to assume a position which may cause the vehicle to operate in an undesired manner).
It is a first object of the present invention to provide a shift motor encoder assembly and a method for utilizing the shift motor encoder assembly in a manner which overcomes some or all of the previously delineated drawbacks of prior assemblies.
It is a second object of the present invention to provide a shift motor encoder assembly and a method for utilizing the shift motor encoder assembly in a manner which overcomes some or all of the previously delineated drawbacks of prior assemblies and which employs a robust and error resistant binary encoding methodology.
It is a third object of the present invention to provide a shift motor encoder assembly and a method for utilizing the shift motor encoder assembly in a manner which overcomes some or all of the previously delineated drawbacks of prior assemblies and which causes open circuit type faults to be xe2x80x9cvisiblexe2x80x9d.
It is a fourth object of the present invention to provide a shift motor encoder assembly and a method for utilizing the shift motor encoder assembly in a manner which overcomes some or all of the previously delineated drawbacks of prior assemblies and which substantially prevents a valid code from being identical to the code of any adjacent position which corresponds to a non-operational position of the motor, upon the occurrence of an open circuit type fault.
It is a fifth object of the present invention to provide a shift motor encoder assembly and a method for utilizing the shift motor encoder assembly in a manner which overcomes some or all of the previously delineated drawbacks of prior assemblies and which substantially prevents the code which is associated with the neutral position to be identical to a code which represents a main stop position with an open circuit type fault.
It is a sixth object of the present invention to provide a shift motor encoder assembly and a method for utilizing the shift motor encoder assembly in a manner which overcomes some or all of the previously delineated drawbacks of prior assemblies and which does not have any position (main stop, intermediate or rail) wit h the code identical to the power loss code.
According to a first aspect of the present invention a shift motor encoder assembly is provided and comprises an encoder which generates a code for a position of the motor having a certain number of logically high signals depending upon the likelihood that the motor will assume that position; and a controller which is communicatively coupled to the encoder and which receives the code.
According to a second aspect of the present invention a method is provided for assigning codes to main stop motor positions and a neutral position. The method includes the steps of assigning a unique code to each of the main stop motor positions and the neutral position and preventing or substantially reducing the likelihood that the neutral position code will be identical to any of the main stop motor positions upon the occurrence of an open circuit fault.
According to a third aspect of the present invention a method is provided for generating codes for use by a shift motor encoder which is operatively disposed in a four wheel drive transfer assembly. The method includes the steps of substantially preventing or substantially reducing the likelihood that, upon the occurrence of an open circuit fault, a main stop code will be identical to the code of any adjacent position.